Distillation of sweetened petroleum distillates



Patented Apr. 28, 1953 DISTILLATION F SWEETENED PETROLEUM DISTILLATES Roger D. Barr, Baytown, -Tex., assignor, by mesne'] f assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware No Drawing. 1 Application February 19,1951,

"Serial No. 211,813

Claims. 1

The present invention is directed to a-method of distilling. a treated hydrocarbon fraction boiling in the gasoline and kerosene boiling ranged. More particularly, the invention is di rected to the distillation of sweetened petroleum distillates boiling below 600 F. to obtain an over position, by admixing at least a partially sweet-,-

ened fraction with a treating reagent comprising a hydrocarbon fraction boiling in the lubricat-- ing oil boiling range, an alkali metal sulfonate,

The admixture and an alkali metal hydroxide. is then subjected to distillation conditions to recoverfrom the distillation operation a doctor sweet overhead fraction which is substantially free of mercaptans and disulfides.

The treating mixture employed in the present.

invention will usually comprise an oil boiling in the lubricating oil boiling range, an alkali metal sulfonate such as a sodium sulfonate produced by sulfonation of a solvent extract of a lubricating oil fraction and subsequent neutralization thereof; and an alkali metal hydroxide.

such as sodium hydroxide.

The alkali metal hydroxide is preferably sodium hydroxide, but potassium and lithium hydroxides may be substituted therefor.

The alkali metal sulfonate is preferably sodium sulfonate, but, like the alkali metal hydroxide, may be potassium sulfonate or lithium sulfonateand-under some conditions ammonium sulfonates maybe satisfactory.

The oil forming a portion of the treating mixture is preferably an oil boiling in the lubricating oil boiling range and may be a solvent extract of a lubricating oil fraction.

The sulfonates, as mentioned before, may be formed by sulfonation and subsequent neutralization of a solvent extract of a lubricating oil fraction, but may also be formed by sulfon'ation and subsequent neutralization of alkyl aromatics,

which, in turn, may be produced by alkylation" of aromatic hydrocarbons such as toluene and benzene with high molecular weight olefins hav-' ing more than five carbon atoms in the side chain.- -A satisfactory treating reagent may be ob' tained by treatment of a solvent extract such as a phenol extract of a lubricating oil fraction with strong sulfuricacid tocause sulfona'tion sulfonate and sodium hydroxide.

of the aromatic constituents contained therein followed by separation of the sludge and neu-. tralization of the oil layer containing sulfonated derivatives with sodium hydroxide to form a mixture containing oil, sodium .sulfonates, and a small amount of sodium hydroxide. To this mixture is added an amount of sodium hydroxide between about one to weight per cent of the mixture. While such a treating reagent may be formed by employing an excess of sodium hydroxide in the neutralization, it is to be understood that the treating reagent may be formed by compounding lubricating oil fractions, sodium sulfonates from any source, and sodium hy droxide. g

The treating reagent, prior to the addition of the sodium hydroxide. should contain an amount of oil such as a lubricating oil fraction or a sol-- vent extract of a lubricating oil fraction in the range from about to and the alkali metal sulfonate, such as sodium sulfonate, should be present in the mixture prior to the addition of the alkali metal hydroxide in an amount in the range between 10% and 25%. Such a mixture is readily formed by sulfonation of a solvent extract, such as a phenol extract, with strong sulfuric acid, followed by neutralization of the oily layer with sodium hydroxide. A base treating mixture which has given good results, after addition of sodium hydroxide, comprises about 90% unsulfonated phenol extract and about-10% sodium sulfonates. H

The invention will be further illustrated by reference to a number of distillations in which a solvent raffinate of a kerosene fraction which had an original copper number of 38 was sweetened. One portion was sweetened in an oxidative sweetening process and a second portion thereof was sweetened by contacing same with a hypochlorite solution. The portion which was sweetened in the oxidative sweetening process was divided into first and second batches and the first batch was distilled over a treating reagent. comprising a hydrocarbon fraction boil ing in the lubricating oil boiling range, sodium The other batch of sweetened solvent raffinate was admixed with a mixture of sodium naphthenates, sodium hydroxide and oil; the two batches were thendistilled to recover four different fractions. amounting to 20% increments of the charge.-

The hypochlorite sweetened sample was also distilled over the treating reagent disclosed in the present invention. In each run where the treating reagent was employed it was used in an Table I like, may be used following which the distillate to which the promoter is added is contacted with alkali metal hydroxide solution in the presence of an oxidizing agent, such as air. Since the sweetening process employed to sweeten the feed Stock of the present invention does not form a part thereof further details of the sweetening Copper Number Fraction from Distillation, Vol. Per -100 (Charge).-

cen Oxygen Sweetened:

Treating Reagent 1 1 1 No Treating Reagent l 2 7 Hypoehlorite Sweetened:

Treating Reagent 0 (Pass Dr.). 0-i 0-1- No Treating Reagent. 0 (Pass Dr.)... 2 3 Oxygen Sweetened:

Sodium Naphthenates, Sodium 1-2 8 6 Hydroxide and Oil.

It will be seen from the foregoing data that the solvent raffinate which had been sweetened in the oxidative sweetening process had a copper number of l and when distilled over the treating agent disclosed in the present invention the four fractions recovered as overhead had copper numbers ranging from 1 to 2. On comparing this run with the portion distilled in the absence of, a treating agent it will be seen that the copper numbers of the fractions therefrom ranged from 2 to 36 indicating decomposition of disulfides present in the charge to the distillation operation. Considering the two distillations of the hypochlorite sweetened solvent rafiinate, it will be seen that the four fractions recovered from distillation in the presence of the treating reagent had copper numbers ranging from 0 to 3, whereas when no treating reagent was employed the copper numbers of the overhead fracas is well known in the art, the overhead fractions had copper numbers ranging from 8 to 45, substantially greater than that obtained in the practice of the present invention and greater than the original copper number of the unsweetened kerosene, which was 38. The product from the foregoing runs, in accordance with the present invention had very low copper numbers but did not in every instance pass the doctor test. This was due to the severity of the distillation conditions. head fraction may be obtained in the practice of my invention which issweet or substan-. tially sweet. If the product does not pass the doctor test it may be subjected to further treating operations.

The invention is also applicable to gasoline and kerosene fractions which have been sweetened by other treating processes, such as treat-- ing processes employing doctor solution. The doctor solution is well known to the art and a method of applying same will not be given in detail here. Likewise, the hypochlorite sweetening process in which an alkaline hypochlorite treating reagent is used. The oxidative sweetening process employed to sweeten the solvent extract in the aforementioned examples is one wherein a promoter for the sweetening reaction is added to the naphtha or kerosenes being sweetened. For example, a suitable phenolic compound, such as petroleum phenols and the It is contemplated that an overi ill) operation will not be given. It will sufdce to say that the feed stock of the present invention may be sweetened or partially sweetened by any operation which converts mercaptans to mercaptides and provides a sweetened or partially sweetened gasoline or kerosene which contains mercap'tides and which passes or nearly passes the doctor test. If the feed stock is partially sweetened the copper number should be no reater than 5 for best results.

In the foregoing examples, the improvement obtained by the practice of the present invention has been illustrated by the copper number test. This is a well known analytical procedure in the petroleum industry. A description of the method of test may be found in U. 0. P. Laboratory Test Methods for Petroleum and Its Products, third edition, page H-Sl, Universal Oil Products 00., Chicago, 1947. This test is a measure of the mercaptan sulfur content of the oil being tested.

The nature and objects of the present inven tion having been completely described and illustrated, whatI wish to claim as new and useful and to secure by Letters Patent is:

l. A method for distilling a treated hydrocarbon fraction which comprises admixing at least a substantially sweetened fraction boiling in the gasoline and, kerosene boiling range and containing disulfides susceptible to thermal decomposition with a treating reagent comprising a hydrocarbon fraction boiling in the lubricating oil boiling range, an alkali metal sulfonate, and an alkali metal hydroxide, subjecting the admixture to distillation conditions and recovering from distillation an overhead fraction sub stantially free of mercaptans and. disulfides.

2. A method in accordance with claiml in which the sweetened fraction is admixed with an amount of the treating reagent in the range from about 5 to about 30 volume per cent.

3. A method in accordance with claim 1 in which the fraction boiling in the lubricating 'oil boiling range is a solvent extract of a lubricating oil fraction, the alkali metal sulfonate is sodium sulfonate and. the alkali metal hydroxide is sodium hydroxide.

4. A method for distilling a treated hydrocarbon fraction which comprises admixing at least a substantially sweetened fraction boiling below 600 F. and containing disulfides susceptible to decomposition with a treating reagent comprising to of a hydrocarbon fraction boiling in the lubricating oil boiling range, 10% to 25% of an alkali metal sulfonate to which has been added anamount of an alkali metal hydroxide sufiicient to provide an amount of alkali metal hydroxide in said treating agent in the range between one and 50%, subjecting the admixture to distillation conditions and recovering from said distillation an overhead fraction substantially free of mercaptans and disulfides.

5. A method in accordance with claim 4 in which the sweetened fraction is admixed with an amount of treating reagent in the range from about 5 to about 30 Volume percent.

6. A method in accordance with claim 4 in which the fraction boiling in the lubricating oil boiling range is a solvent extract of a lubricating oil fraction, the alkali metal sulfonate is sodium sulfonate and the alkali metal hydroxide is sodium hydroxide.

'7. A method for distilling a treated hydrocarbon fraction which comprises admixing a partial- 1y sweetened fraction boiling in the gasoline and kerosene boiling range and containing disulfides susceptible to thermal decomposition and having a copper number no greater than 5 with a treating reagent comprising a hydrocarbon fraction boiling in the lubricating oil boiling range, an alkali metal sulionate and an alkali metal hydroxide, subjecting the admixture to distillation conditions and recovering from said distillation a substantially doctor sweet overhead fraction substantially free of mercaptans and disulfides.

8. A method in accordance with claim 7 in which the hydrocarbon fraction is admixed with an amount of the treating reagent in the range from about 5 to about 30 volume per cent.

9. Amethod in accordance with claim 7 in which the fraction boiling in the lubricating oil boiling range is a solvent extract of a lubricating oil fraction, the alkali metal sulfonate is sodium sulfonate and the alkali metal hydroxide is sodium hydroxide.

10. A method for distilling a treated hydrocarbon fraction which comprises admixing a sweetened solvent raffinate boiling in the kerosene boiling range and containing disulfides susceptible to thermal decomposition with a treating reagent comprising 15% to 90% of a hydrocarbon fraction boiling in the lubricating oil boiling range, 10% to 25% of an alkali metal sulfonate to which has been added an amount of an alkali metal hydroxide sufiicient to provide an amount of alkali metal hydroxide in said reagent in the range between one and subjecting the admixture to distillation conditions and recovering from said distillation a substantially doctor sweet overhead fraction substantially free of mercaptans and disulfides.

ROGER D. BARR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,740,584 Gardner Dec. 24, 1929 2,105,874 Aldridge et a1 Jan. 18, 1938 2,563,605 Jones et a1 Aug. 7, 1951 

1. A METHOD FOR DISTILLING A TREATED HYDROCARBON FRACTION WHICH COMPRISES ADMIXING AT LEAST A SUBSTANTIALLY SWEETENED FRATION BOILING IN THE GASOLINE AND KEROSENE BOILING RANGE AND CONTAINING DISULFIDES SUSCEPTIBLE TO THERMAL DECOMPOSITION WITH A TREATING REAGENT COMPRISING A HYDROCARBON FRACTION BOILING IN THE LUBRICATING OIL BOILING RANGE, AN ALKALI METAL SULFONATE, AND AN ALKALI METAL HYDROXIDE, SUBJECTING THE ADMIXTURE TO DISTILLATION CONDITIONS AND RECOVERING FROM SAID DISTILLATION AN OVERHEAD FRACTION SUBSTANTIALLY FREE OF MERCAPTANS AND DISULFIDES. 